We found that compared with that in NLVM samples, the number of CD68+ macrophages in the FLVM samples was significantly increased, and this cell subset comprised mainly CD68+CD206+ M2 macrophages (Fig. 1B, C), and the number of CD206+ M2 macrophages in the FLVM samples was higher than that in NLVM, although the proportion of M2 macrophages was slightly higher in the tissues from people without HF (Supplementary Fig. A). Here, MRC1 is linked to hydrops fetalis.